A CPU operating based on programs is incorporated in an audio apparatus such as an amplifier, a DVD player or the like. Of these programs, programs to be placed between hardware and software are generally referred to as firmware. When the firmware is stored in a flash memory or the like in advance, addition of functions or correction of defects can be performed later.
Patent Document 1 discloses an apparatus as follows. That is, the mode of the apparatus is switched to an upgrade mode to rewrite firmware. Data for rewriting the firmware are input from a digital audio signal input terminal or another terminal. The data are written properly over a reproduction processing program region of a memory. Thus, the firmware is upgraded.
Patent Document 1: JP-A-2002-149428